第二次执行后台工作程序时出现 InvalidOperationException

发布于 2024-12-02 16:40:49 字数 880 浏览 1 评论 0原文

我正在 vb2010 Express 中使用 wpf 和 vb.net 制作一个应用程序，并且遇到一个让我发疯的问题。

我有一个每分钟执行一次后台工作程序的计时器：

Private Sub timer_Tick() Handles timer.Tick
    If Not bworker.IsBusy Then
        bworker.RunWorkerAsync()
    End If
End Sub

后台工作程序正在使用 xmlelement 和 xmldataprovider：

Private Sub bworker_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bworker.DoWork
    Dim source As XmlDataProvider = Application.Current.Resources("r1")
    Dim sometext As String = "something"
    Dim elemento As XmlElement = source.Document.CreateElement("elemento")
    elemento.InnerText = sometext
    e.Result = elemento
End Sub

然后我在 RunWorkerComplete 上使用 e.Result 将 XmlElement 添加到源。我第一次执行后台工作程序时它工作得很好，但是当计时器第二次调用它时，它会在“elemento.InnerText = sometext”行中抛出 InvalidOperationException ，为什么会这样以及如何解决它？

原文

I'm making an app using wpf and vb.net in vb2010 express and having a problem that is driving me crazy.

I have a timer that execute a backgroundworker every minute:

Private Sub timer_Tick() Handles timer.Tick
    If Not bworker.IsBusy Then
        bworker.RunWorkerAsync()
    End If
End Sub

The backgroundworker is working with xmlelement and xmldataprovider:

Private Sub bworker_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bworker.DoWork
    Dim source As XmlDataProvider = Application.Current.Resources("r1")
    Dim sometext As String = "something"
    Dim elemento As XmlElement = source.Document.CreateElement("elemento")
    elemento.InnerText = sometext
    e.Result = elemento
End Sub

Then I'm using e.Result on RunWorkerComplete to add the XmlElement to source. It works perfect the first time I execute the backgroundworker, but when the timer calls it the second time it throws a InvalidOperationException in the line "elemento.InnerText = sometext" why is that and how can I solve it?

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